Fuel injector for internal-combustion engines



ct. 0 5 2 w. B. POTTER FUEL INJECTOR FOR INTERNAL COMBUSTION ENGINES Filed Feb. 6. 1925 Im/entor:

William B. potter, by fi- M His Attorney.

Patented Get. .11, 192?.

UNET 3T5 er r WILLIAM B. POTTER, OF SCHENECTADY, NEW YORK, ASSIGNOR T0 GENERAL ELEGTRIC COMPANY, A CORPORATION OF NEW YORK.

FUEL INJECTOR FOR INTERNAL-COMBUSTION ENGINES.

Application filed February 6, 1923, Serial No. 617,368, and in Great Britain July 18, 1922.

The present invention relates to fuel injectors for internal combustion engines and particularly to fuel injectors for use with engines having what is usually termed solid injection, although it is not necessarily limited thereto. It will be understood that by solid injection is meant engines wherein the fuel is forced by the pump directly through the nozzle into the cylinder without the use of blast air, the nozzle serving to break up the fuel charge into a fine spray.

In connection with the operation of engines of this type the fuel is forced through the nozzle at a high pressure and difliculty has been experienced in that after the pressure is removed on completion of the pump discharge stroke, the contraction of the iping system and inertia of the fuel oil cause a slight after flow through the nozzle but at such a low pressure that the oil only oozes out of the end of the nozzle and is not atomized. In this connection,'it will be understood that this after-flow or dribbling is a transient effect which takes place only at the moment when the pressure in the supply pipe is relieved and does not extend throughout.

the entire period between pressure strokes. While the quantity of this after flow is small, it is in liquid form and being spread over the nozzle surfaceits fuel value is practically lost and so decreases the engine efliciency. The resence of this unconsumed fuel oil tends also to cause a smoky exhaust and the formation of carbon in the cylinder especially around the end of the nozzle.

The object of my invention is to provide an improved fuel nozzle which will overcomein an efficient manner-the above referred to difiiculty and for a consideration of what I believe to be novel and my invention, attention is directed to the accompan ing description and the claims appended t ereto.

In the drawing, Fig. 1 is a sectional view of an internal combustion engine equipped with a fuel injector embodying my invention; Fig. 2 is a sectional view of the fuel injector, and Fig. 3 is a sectional view on a larger scale of the discharge end of the injector.

Referring to the drawing, 5 indicates the cylinder, 6 the piston and 7 the cylinder head of an internal combustion engine. Mounted on cylinder head 7 is a fuel injector comprising a casing 8 which threads into an opening in head 7 and has an orifice 9 through which the fuel oil is sprayed into the cylinder. Mounted in casing 8 is a member 10 provided with an axial admission passage or.

opening 11 which at its inner end is enlarged to form with the inner end of easing 8 a chamber 12 in advance of orifice 9; Connected to the outer end of openin 11 is a fuel supply pipe 13 which leads from any suitable fuel supply such as the usual fuel ump.

In the drawing I have indicated a fuel pump diagrammatically at 14, the suction pipe being indicated at 14 and the dischar e pipe at 13. The pump plunger 145 may e operated in any suitable manner usually from the engine by a suitable cam 14.

The operation of an arrangement as so far described is well known and needs no further description, the general arrangement being typlical of engines of this character.

l ow, according to my invention, I provide in connection with the fuel nozzle or injector a device which forms a sort of pump means for sucking or drawing the fuel oil back from the nozzle discharge orifice immediately the pump or fuel stroke is completed so that any after flow of fuel oil through the nozzle orifice is prevented. This pump means is preferably operated by the pressure of the fuel oil itself so that it comes into action immediately the fuel pump pressure ceases.

In the embodiment of the invention illustrated, this pump means is in the form of a flexible plate or spring plate 15 which extends across the nozzle between admission passage 11 and discharge orifice 9 and is provided with a. small hole 16 through which the fuel oil flows on its way to orifice 9. Behind plate 15 is a disc 17 which is referably concave and forms a stop and bac g member for plate 15. Disk 17 is provided with suitable openings 18 for the passage of the fuel oil. 1

Assume that the engine is running and that pump 14 is supplying fuel to it. Assume also that the pum has just completed its suction stroke and is about to start on the discharge stroke. Under these circumstances pi e line 13 and passage 11 will be full of oi the oil standing up to orifice 9, and disk 15 will occupy a position as shown in the drawing. Now, on the. discharge stroke of the ump, oil will be forced past the usual disc arge valve or check valve,

discharge stroke of the such valve being forced open a certain amount, and through pipe 13, passage 11 and orifice 9 into the engine cylinder, the oil being atomized as it passes through the orifice. During the discharge stroke, disk 15 will be deflected toward orifice 9 by the pressure of the oil against it. As soon as the pump is completed or the required amount of 011 is delivered, the discharge or check valve which has been opened on the discharge stroke, will move back to its seat. This relievesslightly the pressure in pipe 13 and permits a slight flow of oil backward in the pipe, the amount depending upon the distance which the check valve must move in returning to its seat and the amount of oil which may escape back past the check valve before it is seated. In any event, a limited flow of oil backward in the pipe line may take place. This permits late 15 to spring back and such springing ack serves to check further flow of oil through orifice 9, and at the same time to withdraw or suck back slightly the oil di-' rectly adjacent to and in the outer end ofv orifice 9, thus preventing dribbling. In this connection, it will be understood that the actual required movement of plate 15 is slight, it being necessary that only a minute quantity of 011 be withdrawn from the end of the nozzle in order to prevent dribbling. It will be understood, also, that during the suction stroke of the pump, oilwill not flow of its own volition through orifice 9v into the cylinder because of its viscosity.

In accordance with the provisions of the patent statutes, I have described the princi le of operation of my invention, together with the apparatus which I now consider to re resent the best embodiment thereof; but I desire to have it understood that the appaof fuel oil ratus shown is only illustrative, and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is,-

1. In a fuel injector for internal combustion engines, a body having an admission opening, a discharge orifice for atomizing the fuel and an enlar ed chamber in advance of the discharge orifice, and a flexible disk which extends across said enlarged chamber and is provided with an opening through which the fuel oil flows to the discharge orifice, the flexibility of said disk being such that it is flexed by the oil pressure upon the discharged stroke of the pump and springs back when the oil pressure is relieved whereby it serves as a pump to effect withdrawal from the end of the discharge orifice after each fuel charge is supplied to the engine.

2. In a fuel injector for internal combustion engines, a body having an admission opening, a discharge orifice for atomizing the fuel and an enlarged chamber in advance of the discharge orifice, a flexible disk which extends across said enlarged chamber and is provided with an opening through which the fuel oil flows to the discharge orifice, the flexibility of said disk being such that it is flexed by the oil pressure upon the discharged stroke of the pump and springs back when the oil pressure is relieved whereby it serves as a pump to effect withdrawal of fuel oil from the end of the discharge orifice after each fuel charge is supplied to the engine, and a etc for ward movement of said disk.

In witness whereof, I have hereunto set my hand this 5th day of February, 1923.

WILLIAM B. POTTER.

limiting the forp 

